The Effect of Co-Crystallising Sulphides and Precipitation Mechanisms on Sphalerite Geochemistry: A Case Study from the Hilton Zn-Pb (Ag) Deposit, Australia

High-tech metals including Ge, Ga and In are often sourced as by-products from a range of ore minerals, including sphalerite from Zn-Pb deposits. The Hilton Zn-Pb (Ag) deposit in the Mount Isa Inlier, Queensland, contains six textural varieties of sphalerite that have formed through a diverse range of processes with variable co-crystallising sulphides. This textural complexity provides a unique opportunity to examine the effects of co-crystallising sulphides and chemical remobilisation on the trace element geochemistry of sphalerite. Early sphalerite (sph-1) is stratabound and coeval with pyrrhotite, pyrite and galena. Disseminated sphalerite (sph-2) occurs as isolated fine-grained laths rarely associated with co-crystallising sulphides and represents an alteration selvage accompanying the precipitation of early stratabound sphalerite (sph-1). Sphalerite (sph-3) occurs in early ferroan-dolomite veins and formed from the chemical remobilisation of stratabound sphalerite (sph-1) during brittle fracturing and interstitial fluid flow. This generation of veins terminate at the interface, and occurs within clasts of the paragenetically later sphalerite-dominated breccias (sph-4). Regions of high-grade Cu (>2%) mineralisation contain a late generation of sphalerite (sph-5), which formed from the recrystallisation of breccia-type sphalerite (sph-4) during the infiltration of a paragenetically late Cu- and Pb-rich fluid. Late ferroan-dolomite veins crosscut all previous stages of mineralisation and also contain chemically remobilised sphalerite (sph-6). Major and trace elements including Fe, Co, In, Sn, Sb, Ag and Tl are depleted in sphalerite associated with abundant co-crystallised neighbouring sulphides (e.g., pyrite, pyrrhotite, galena and chalcopyrite) relative to sphalerite associated with minor to no co-crystallising sulphides. This depletion is attributed to the incorporation of the trace elements into the competing sulphide minerals. Chemically remobilised sphalerite is enriched in Zn, Cd, Ge, Ga and Sn, and depleted in Fe, Tl, Co, Bi and occasionally Ag, Sb and Mn relative to the primary minerals. This is attributed to the higher mobility of Zn, Ge, Ga and Sn relative to Fe and Co during the chemical remobilisation process, coupled with the effect of co-crystallising with galena and ferroan-dolomite. Results from this study indicate that the consideration of co-crystallising sulphides and post-depositional processes are important in understanding the trace element composition of sphalerite on both a microscopic and deposit-scale, and has implications for a range of Zn-Pb deposits worldwide.

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Trace element geochemistry of a Precambrian diabase dike from western Ontario

Canadian Journal of Earth Sciences ◽

10.1139/e77-255 ◽

1977 ◽

Vol 14 (12) ◽

pp. 2941-2944 ◽

Cited By ~ 12

Author(s):

J. Dostal ◽

M. Fratta

Keyword(s):

Trace Elements ◽

Trace Element ◽

Trace Element Geochemistry ◽

Element Geochemistry

A diabase dike of the Precambrian Mackenzie swarm from western Ontario has been sampled at two localities where it intrudes basaltic volcanics and granite respectively. The two profiles across the dike have rather similar contents of major and some trace elements (REE, U, Zr, Hf, Y, Nb, Sc, Co, Cr, and Sc) but differ in the abundances of K and related elements (Rb, Tl, Li, and Ba), which are significantly higher in the section of the dike intruding the granite. The differences can probably be attributed to selective contamination from granitic country rocks by diffusion.

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ReOs isotopes and major and trace element geochemistry of carbonaceous shales, Aravalli Supergroup, India: Impact of post-depositional processes

Chemical Geology ◽

10.1016/j.chemgeo.2013.06.014 ◽

2013 ◽

Vol 354 ◽

pp. 93-106 ◽

Cited By ~ 6

Author(s):

Gyana Ranjan Tripathy ◽

Sunil Kumar Singh ◽

Harsh Bhu

Keyword(s):

Trace Element ◽

Trace Element Geochemistry ◽

Element Geochemistry ◽

Depositional Processes ◽

Carbonaceous Shales ◽

Aravalli Supergroup

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Trace Element Heterogeneity Across Individual Planktic Foraminifera from the Modern Cariaco Basin

The Journal of Foraminiferal Research ◽

10.2113/gsjfr.50.2.204 ◽

2020 ◽

Vol 50 (2) ◽

pp. 204-218

Author(s):

Catherine V. Davis ◽

Jennifer S. Fehrenbacher ◽

Claudia Benitez-Nelson ◽

Robert C. Thunell

Keyword(s):

Trace Element ◽

Environmental Variability ◽

Single Species ◽

Large Degree ◽

Trace Element Composition ◽

Cariaco Basin ◽

Trace Element Geochemistry ◽

Element Geochemistry ◽

Planktic Foraminifera ◽

Species Specific

ABSTRACT The trace element composition of planktic foraminifera shells is influenced by both environmental and biological factors (‘vital effects’). As trace elements in individual foraminifera shells are increasingly used as paleoceanographic tools, understanding how trace element ratios vary between individuals, among species, and in response to high frequency environmental variability is of critical importance. Here, we present a three-year plankton tow record (2010–2012) of individual shell trace element (Mg, Sr, Ba, and Mn) to Ca ratios in the planktic species Globigerina ruber (pink), Orbulina universa, and Globorotalia menardii collected throughout the upper 100 m of Cariaco Basin. Plankton tows were paired with in situ measurements of water column chemistry and hydrography. The Mg/Ca ratio reflects different calcification temperatures in all three species when calculated using species-specific temperature relationships from single-species averages of Mg/Ca. However, individual shell Mg/Ca often results in unrealistic temperate estimates. The Sr/Ca ratios are relatively constant among the four species. Ratios of Mn/Ca and Ba/Ca are highest in G. menardii and are not reflective of elemental concentrations in open waters. The Mn/Ca ratio is elevated in all species during upwelling conditions, and a similar trend is demonstrated in Neogloboquadrina incompta shells from the California margin collected during upwelling periods. Together this suggests that elevated shell Mn/Ca may act as a tracer for upwelling of deeper water masses. Our results emphasize the large degree of trace element variability present among and within species living within a limited depth habitat and the roles of biology, calcification environment, and physical mixing in mediating how trace element geochemistry reflects environmental variability in the surface ocean.

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Corundum Anorthosites-Kyshtymites from the South Urals, Russia: A Combined Mineralogical, Geochemical, and U-Pb Zircon Geochronological Study

Minerals ◽

10.3390/min9040234 ◽

2019 ◽

Vol 9 (4) ◽

pp. 234 ◽

Cited By ~ 2

Author(s):

Maria I. Filina ◽

Elena S. Sorokina ◽

Roman Botcharnikov ◽

Stefanos Karampelas ◽

Mikhail A. Rassomakhin ◽

...

Keyword(s):

Trace Element ◽

Inductively Coupled Plasma ◽

Trace Element Composition ◽

South Urals ◽

Trace Element Geochemistry ◽

The South ◽

Element Geochemistry ◽

Inductively Coupled ◽

Geochronological Study ◽

Lower Temperature

Kyshtymites are the unique corundum-blue sapphire-bearing variety of anorthosites of debatable geological origin found in the Ilmenogorsky-Vishnevogorsky complex (IVC) in the South Urals, Russia. Their mineral association includes corundum-sapphire, plagioclase (An61–93), muscovite, clinochlore, and clinozoisite. Zircon, churchite-(Y), monazite-(Ce), and apatite group minerals are found as accessory phases. Besides, churchite-(Y) and zircon are also identified as syngenetic solid inclusions within the sapphires. In situ Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U-Pb zircon geochronology showed the ages at about 290–330 Ma linked to the Hercynian orogeny in IVC. These ages are close to those of the syenitic and carbonatitic magmas of the IVC, pointing to their syngenetic origin, which is in agreement with the trace element geochemistry of the zircons demonstrating clear magmatic signature. However, the trace element composition of sapphires shows mostly metamorphic signature with metasomatic overprints in contrast to the geochemistry of zircons. The reason for this discrepancy can be the fact that the discrimination diagrams for sapphires are not as universal as assumed. Hence, they cannot provide an unambiguous determination of sapphire origin. If it is true and zircons can be used as traces of anorthosite genesis, then it can be suggested that kyshtymites are formed in a magmatic process at 440–420 Ma ago, most probably as plagioclase cumulates in a magma chamber. This cumulate rock was affected by a second magmatic event at 290–330 Ma as recorded in zircon and sapphire zoning. On the other hand, Ti-in-zircon thermometer indicates that processes operated at relatively lower temperature (<900 °C), which is not enough to re-melt the anorthosites. Hence, zircons in kyshtymites can be magmatic but inherited from another rock, which was re-worked during metamorphism. The most probable candidate for the anorthosite protolith is carbonatites assuming that metamorphic fluids could likely leave Al- and Si-rich residue, but removed Ca and CO2. Further, Si is consumed by the silicification of ultramafic host rocks. However, kyshtymites do not show clear evidence of pronounced metasomatic zonation and evidence for large volume changes due to metamorphic alteration of carbonatites. Thus, the obtained data still do not allow for univocal reconstruction of the kyshtymite origin and further investigations are required.

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